1. Technical Field
The present invention relates to a feeding device that includes a pickup roller picking up a loaded feeding medium and sending the feeding medium to a downstream side of a feeding direction and a regulator provided at a location different from that of the pickup roller so as to regulate a posture of the feeding medium, and a printing apparatus that includes the feeding device. An example of the printing apparatus includes as an ink jet printer, a wire dot printer, a laser printer, a line printer, a copying machine, a facsimile machine, or the like.
2. Related Art
As disclosed in JP-A-2006-312504 and JP-A-2006-117393, a feeding device provided in a printing apparatus includes a pickup roller and a regulator. Among them, the pickup roller is configured to pick up a loaded feeding medium, that is, a paper sheet and to send the feeding medium to a downstream side of a feeding direction. In addition, the regulator is configured to regulate the posture of the paper sheet.
FIGS. 16A and 16B are front views illustrating a schematic configuration inside a known printing apparatus when viewed from a downstream side of a feeding direction. Here, FIG. 16A illustrates the printing apparatus disclosed in JP-A-2006-312504. FIG. 16B illustrates the printing apparatus disclosed in JP-A-2006-117393.
As shown in FIG. 16A, a feeding device 201 provided in a printing apparatus 200 disclosed in JP-A-2006-312504 includes a pickup roller 202, a holder unit 203, and regulators 204. Here, the pickup roller 202 is configured to pick up a paper sheet 205 and to send the paper sheet 205 to a downstream side of a feeding direction (direction Y). In addition, the holder unit 203 is configured to retain the pickup roller 202 so that the pickup roller 202 is movable in a direction contacting with or separating from the paper sheet 205.
The regulators 204 are integrally formed with the holder unit 203 and are disposed in the vicinity of the inside of both side ends in a widthwise direction X of the paper sheet 205 so as to regulate the posture of the paper sheet 205, that is, the uplift (simply referred to as “lift”) of the paper sheet 205. That is, the regulators 204 are fixed to the holder unit 203.
In addition, when the pickup roller 202 picks up the paper sheet 205, the friction force is generated between the pickup roller 202 and the paper sheet 205. For this reason, the pickup roller 202 is urged in a direction approaching the paper sheet 205 by the holder unit 203. The urging force is referred to as the pickup urging force G (“G1” in JP-A-2006-312504 and “G2” in JP-A-2006-117393).
In JP-A-2006-312504, the pickup urging force G1 is 100 gram-weight. The pickup urging force G1 is set to generate the appropriate friction force against the paper sheet 205. Accordingly, the pickup roller 202 can pick up the uppermost paper sheet 205 and send the paper sheet 205 to a downstream side of a feeding direction. Here, the uppermost paper sheet indicates the paper sheet which is the closest to the pickup roller 202.
However, since the lift phenomenon of the paper sheet 205 indicates the state where both sides of the paper sheet are deformed due to the absorbed moisture or the like, this lift phenomenon occurs even in the case of a stiff paper sheet. In this case, the side ends of the stiff paper sheet 205 may directly contact with the regulators 204 so as to strongly push upward the holder unit. Accordingly, the pickup roller 202 may be moved away from the paper sheet 205, so that the pickup roller 202 may not pick up the paper sheet 205. This is a so-called non-feeding state.
Therefore, in JP-A-2006-117393, as shown in FIG. 16B, the pickup urging force G2 is set to 500 gram-weight sufficiently larger than that of JP-A-2006-312504 so as to push downward the lifted paper sheet 205 by using the regulators 204. In addition, since the other components are the same as those of JP-A-2006-312504, the same reference numerals are used and a detailed description thereof will be omitted.
Accordingly, even when the lift phenomenon occurs in the stiff paper sheet, it is possible to prevent the pickup roller 202 from being moved away from the paper sheet 205.
However, another problem arises. In detail, since the pickup urging force G2 is set to 500 gram-weight, the friction force between the uppermost paper sheet 205 and the following paper sheet 205 increases. Accordingly, the large feeding force may be applied to the following paper sheet 205, so that the following paper sheet 205 is simultaneously sent to a downstream side of a feeding direction. This is a so-called overlapping feeding operation. That is, when only the pickup urging force G2 is set to a large value, the pickup precision becomes unstable.